The present invention relates to an electric hand power tool, in particular a hammer drill or an impact hammer drill.
In a known hammer drill or an impact hammer drill disclosed in German patent document DE 28 20 128 a tool receptacle which receives a tool in non-rotatable and axially displaceable manner is coupled with a rotary sleeve provided with a toothed ring in engagement with a transmission toothed wheel arranged on a transmission shaft. An impact mechanism has a drive piece which is guided reciprocatingly and axially displaceably in the rotary sleeve, and a striker which is striken by the drive piston through an air cushion and transmits its impact energy to the tool which is held axially displaceable in the tool receptacle. The drive piston is driven through a swinging drive from the transmission shaft. The swinging drive has a drive bearing non rotatably seated on the transmission shaft and formed by two drum halves. The drum halves form therebetween a ring groove with a ring axis extending at an acute angle to the shaft axis, and a ring is rotatably held in the ring groove. A radially extending drive piston arranged on the ring engages with a clearance in a transverse opening located inside a rotary pin. The rotary pin in turn engages a fork-shaped end of the drive piston located at a side facing away from the striker. The transmission toothed wheel seated non rotatable on the transmission shaft engages, for rotation of the transmission shaft, with a drive pinion which is formed on a driven shaft of an electric motor. By turning on the electric motor the transmission shaft is set in rotation, and through the intermediate transmission the rotary sleeve and thereby the tool is turned, and the impact mechanism is set in operation through the swinging drive. A device for turning off of the impact mechanism is not provided.
Electric hand power tools are known, in which for turning off the impact mechanism in an operational state “rotary drilling” the drive bearing of the swinging drive sits loose on the transmission shaft and is connected through a manually releasble coupling with a transmission shaft for rotary driving. With manual release of the coupling, the rotary driving between the transmission shaft and the drive bearing of the swinging transmission is lifted and thereby the operation of the switching mechanism is stopped.